Diester based on castor oil fatty acid as plasticizer for poly(vinyl chloride)

ABSTRACT Castor oil is a renewable resource that has potential uses as an environmental friendly material for a range of applications. In recent years, much efforts have been driven to develop alternate plasticizer for medical and commodity plastics due to growing concerns about dioctyl phthalate (DOP) for flexible poly(vinyl chloride) (PVC). In this study, a bio‐based plasticizer was synthesized by a two‐step esterification reaction of castor oil fatty acid (COFA) with benzyl alcohol and octanoic acid in the presence of catalyst (dibutyl tin dilaurate). The structure of the octanoic ester (OE) was confirmed by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, acid value, and hydroxyl value. OE was used as a coplasticizer in PVC for partial replacement of DOP. The addition of OE exhibited good incorporation and plasticizing performance in the PVC sheets. Incorporation of OE resulted in good plasticizing, tensile strength, percentage elongation, exudation, thermal stability, and chemical resistance because of the presence of long carbon chains of COFA. Differential scanning calorimetry (DSC), thermogravimetric analysis, and color measurements were also performed to evaluate the effect of OE. With the increase in OE, DSC and hardness results showed marginal deviation from those obtained for DOP‐plasticized sheets. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 40354.